求救：怎么改.bash_profile?

[weixin_38063619]

有一些命令是在/sbin和/usr/sbin中，我改怎么修改这个文件才能不用没次都输入绝对路径？

# .bash_profile
# Get the aliases and functions
if [ -f ~/.bashrc ]; then
        . ~/.bashrc
fi

# User specific environment and startup programs

PATH=$PATH:/bin

export PATH
unset USERNAME